Recent Investigations of Urinary Nerve Growth Factor as a Biomarker for Overactive Bladder Syndrome

ABSTRACT

PURPOSE: Overactive bladder (OAB) is a symptom syndrome and is usually diagnosed by subjective symptoms of urgency with or without urgency incontinence. However, because urgency symptoms are so subjective, it is difficult to objectively grade symptoms of urgency. Although urodynamic study can detect detrusor overactivity (DO) objectively, not all patients with OAB are found to have DO. Therefore, recent research interests have focused on urinary and image biomarkers in the assessment of OAB. MATERIALS AND METHODS: Investigating articles from the literature and recent published works were reviewed. RESULTS: The urinary nerve growth factor (NGF) level is found to increase in patients with OAB-wet, bladder outlet obstruction, mixed urinary incontinence, and urodynamic DO. NGF levels are correlated with OAB symptoms and return to normal after treatment. However, urinary NGF is not increased only in patients with OAB and DO. It also increases in patients with interstitial cystitis/painful bladder syndrome (IC/PBS) and other lower urinary tract diseases such as urinary tract stones, bacterial infection, and urothelial tumor. Thirty percent of OAB patients have a low urinary NGF level. Nevertheless, antimuscarinic or botulinum toxin treatment can decrease the urinary NGF level, and changes in the NGF level are correlated with the urgency severity scale. CONCLUSIONS: It is therefore possible to use urinary NGF levels as a biomarker for assessment of therapeutic outcome in patients with OAB. Further research on combined multiple biomarkers to differentiate OAB and IC/PBS is necessary.